1. Field of the Invention
The present invention relates to a disk cartridge of sufficient portability accommodating an optical disk, especially to a small-sized disk cartridge of an optical disk of a small diameter.
2. Related Art
Optical disks, as used widely in the prior art, are exemplified by CDs (Compact Disks), MDs (Mini Disks) and DVDs (Digital Versatile Disks). These optical disks are divided into a read only type and a recordable type, which is further divided into an additionally recording only type and a recordable type.
The CD is recorded with non-compressed voice data and compressed graphic and voice data. The MD and the DVD are recorded mainly with compressed image data and voice data.
Optical disks such as CDs and DVDs are mostly used for reproduction only and generally reproduce predetermined strings of data as they are. In an additionally recordable CD-R of a recordable type, a special processing is necessary for editing recorded data because recording is impossible, so that the CD-R is used mostly for producing a small number of CDs or for replicating them. A repeatedly recording type is exemplified by a CD-RW, the number of repetitions of which is restricted so that the recorded data are difficult to freely edit.
Both the CD and the DVD have a diameter of 120 mm or 80 mm. Devices for recording images and voices using them as the recording media are larger in size and poorer in portability than devices using magnetic tapes of 4 mm width as the recording media, so that it damages convenience for the user seriously.
On the other hand, the MD is advantageous in its small size (of a diameter of 64 mm) and in its no eventual restriction on the number of repetitions. However, the MD is given a format requiring a constant linear velocity, i.e., relative speed between a recording head and a medium and is changed in its rotating speed depending upon the radial position so that it is not suited for a high-speed access. Since the MD has the same recording density as the CD but has a smaller diameter than the CD, the MD has a smaller storage capacity and it cannot store massive image data continuously.
The optical disk has a quicker access than that of a take-up type storage device such as a tape. Therefore, the optical disk is featured in that it can rearrange the data quickly on demand by the user without reproducing the recorded data sequentially.
However, since the optical disk of the prior art has a large size, the storage device is given, if the disk of the prior art is used, a large size and a poor portability, so that its range of application is restricted.
If the disk diameter is reduced to give priority to the portability, the storage capacity becomes short and the disk cannot record sufficient data.
When there is a restriction on the number of repetitive recordings, the free edition is also restricted, which make it difficult to enhance additional values of data.
On the other hand, a disk cartridge is inserted in a disk driving device (information recording/reproducing device), so that information is recorded on and reproduced from the optical disk accommodated in the disk cartridge through a head supported by an arm of the disk driving device. Accordingly, the size of the disk cartridge affects the size of the disk driving device.
FIG. 27 shows a schematic construction of a disk device in the state where it is loaded with a disk 1 accommodated in a disk cartridge. In FIG. 27, a permanent magnet 4 is fixed on a turntable 3 of a spindle motor 2 at a portion other than a disk bearing face 5 of the turntable 3. On the disk 1, on the other hand, there is fixed a center hub 7 which is made of a magnetic material and has a center hole 6. The center hole 6 is fitted on a spindle 8 of the spindle motor 2, and the permanent magnet 4 of the turntable 3 attracts the center hub 7 so that the disk 1 is pulled onto the disk bearing face 5. As a result, the disk 1 can be portion for shielding the upper and lower openings; a perpendicular portion jointing the upper and lower shutter portions; a pawl for preventing the shutter from coming off; and a guide portion extending from the perpendicular portion for slidably guiding the shutter, and the upper case is sandwiched between the guide portion and the shutter portion.
Here will be described loading actions to the aforementioned state. The disk 1 is held in a cartridge case 9 so that it can rotate in a loaded state without contact with the cartridge case. Here, the cartridge case 9 is held on a cartridge holder 10, which can rotate on a cartridge holder turning axis 11. On the other hand, the cartridge case 9 retains a positional relation to the spindle motor 2 such that a positioning pin 12 managing the positional relation to the spindle motor is fitted in a positioning hole 13 formed in the cartridge case 9 while keeping the rotating disk 1 out of contact with the cartridge case 9.
FIGS. 28A to 28F show actions from the time when the cartridge is inserted into the cartridge holder to the time when the loading is ended, as shown in FIG. 27. For simplicity, the cartridge holder 10 is omitted from FIGS. 28A to 28F. The loading is performed as follows.
In FIG. 28A, the disk 1 is brought into contact with a lower face of a cartridge inner wall in the cartridge case 9 by the gravitation;
In FIG. 28B, the disk 1 contacts with the lower face of the cartridge inner wall, and a spindle 8 of the spindle motor contacts with a center hub 7;
In FIG. 28C, the disk 1 contacts with the upper face of the cartridge inner wall while being prevented from moving downward by the spindle 8;
In FIG. 28D, the cartridge case 9 moves further downward and a positioning hole 13 provided on the cartridge case 9 starts fitting to a cartridge positioning pin 12;
In FIG. 28E, the cartridge case 9 moves further downward, the spindle 8 fits in the center hole 6 and the cartridge positioning pin 12 fits in the cartridge positioning hole 13; and
In FIG. 28F, the loading actions are ended.
In the loading actions described above, there may arise a problem that the center hub 7 and the spindle 8 of the motor contact midway of the course from FIGS. 28C to 28E so that the spindle 8 and the center hole 6 fail to fit snugly. This is the problem which occurs when the displacement between the center hole 6 and the spindle 8 increases, and is determined by a free stroke of the disk in the cartridge case, that is, the degree of freedom of the disk, the diameter of the center hole, and the diameter of the spindle, and the positional relation between the spindle and the cartridge case. When the degree of a radial freedom of the disk in the cartridge case is about one half or more of the diameter of the spindle, the spindle may fail to be centered within the center hole 8. For reducing the size of the device, the reduction in the size of the spindle motor is naturally demanded. At this time, the spindle diameter naturally has to be reduced so as to lighten the load on the spindle motor. Therefore the aforementioned trouble becomes liable to occur.
A cartridge 2 of a magneto-optic disk MD of the prior art is shown in FIGS. 29A to 29C, FIGS. 30A to 30C and FIGS. 31A to 31C. FIGS. 29A to 29C are diagrams showing a “closed” state of a shutter; FIGS. 30A to 30C are diagrams showing an “open” state of the shutter; and FIGS. 31A to 31C show a magneto-optic recording/reproducing device which is loaded with the cartridge.
In FIGS. 29A to 29C, FIGS. 30A to 30C and FIGS. 31A to 31C, a cartridge 2 is constructed to include an upper cartridge (case) 3, a lower cartridge (case) 5, a shutter 8 and a lock lever 18. An magneto-optic disk 1 to be recorded with information signals is rotatably accommodated in the cartridge 2. The upper cartridge 3 is provided with: a first opening 4 to be faced by a magnetic head 25 for recording/reproducing the information signals; the lower cartridge 5 is provided with a second opening 6 to be faced by a pickup unit 27 for recording/reproducing the information signals; and a third opening 7 to be faced by a spindle motor 26 for rotating/holding the magneto-optic disk 1. Moreover, the cartridge 2 is inserted into a magneto-optic recording/reproducing device 23, as shown in FIGS. 31A to 31C, to record/reproduce the information.
Here will be described the construction of the shutter 8. This shutter 8 is constructed to include: an upper shutter portion 9 and a lower shutter portion 9 for shutting a first opening and a second opening 4 and 6; a perpendicular portion 10 jointing the upper and lower shutter portions 9; pawls 11 for guiding the shutter to be opened/closed and for preventing the shutter from coming off; a guide portion 12 for preventing the pawls 11 from coming off; and a locked portion 13 to be locked by a lock lever 18.
The pawls 11 are attached to slide in a guide groove 14 formed in the lower cartridge 5 to guide and prevent the shutter 8 from sliding out of the cartridge 2. The shutter 8 in a thickness direction of the cartridge 2 by the internal size of the shutter 8 and the contour of the cartridge 2. Moreover, the pawls 11 are confronted by a guide portion 12 for preventing the pawls 11 from coming off in the thickness direction of the cartridge 2 at the time of closing the shutter 8.
With reference to FIGS. 30A to 30C showing the “open” state of the shutter, will be described the cartridge when the shutter is closed and the shielding state of the shutter. In FIGS. 30A to 30C, the shaded portion represents a part of the cartridge 2 covered with the shutter 8 at the closed state. In both FIGS. 30A and 30C, the cartridge 2 is shielded by moving the shutter along one plane.
Like the magneto-optic disk MD, the floppy disk cartridge of 3.5 inches is shielded by moving the shutter along one plane.
Moreover, the magneto-optic disk cartridge of 3.5 inches has an opening even when the shutter is closed, so that it is not completely shielded.
However, the small and thin type highly dense cartridge and magneto-optic disk device of the prior art are troubled by the following problems.
First of all, the shielding of the opening by the shutter 8 is performed by only one plane of the bottom face of the cartridge 2. The guide groove 14 of the shutter 8 is formed in the bottom face, and the actuator of the pickup unit 27 of the magneto-optic disk cannot come close to the magneto-optic disk 1 especially at an outer circumferential position of the disk so that the device has to be large-sized in its entirety. In other words, a holding spring and a magnetic circuit for the actuator have to be positioned apart from the cartridge 2.
In the magneto-optic disk MD, the guide groove 14 and the third opening 7 faced by the actuator are spatially continuous. As a result, dust may contaminate the inside of the disk even when the shutter 8 is closed. The magneto-optic disk cartridge of 3.5 inches is not shielded completely, neither, so that it has similar troubles.